Introduction
The purpose of this experiment was to determine the similarities and differences in the chemical and physical properties of elements and elemental groups. This was achieved by the observation and comparison of chemical reactions of different elements.
Results
Group IA
Reactions in Air:
A piece of lithium, sodium, and potassium we cut with a spatula and introduced with oxygen. The elements appeared to be metallic at first, but over time a white color formed where the element was cut. The balanced chemical reactions for these metals in air are as follows:
4Na(s) + O2(g) 
2Na2O(s)
4K(s) + O2(g) 2K2O(s)
4Li(s) + O2(g) 
2Li2O(s)
Potassium was the fastest element to have this reaction Sodium was in the middle and Lithium was the slowest.
Reactions in Water:
Pieces of the alkali metals were placed into separate beakers of distilled water. Lithium and sodium quickly dissolved in the water creating gas emissions. Potassium sparked and lit on fire and created gas when it touched the water. All three alkali metals left white precipitant at the bottom of the beaker. The pH balances were then tested to find if the solution was basic or acidic.
2Na(s) + 2H2O(l) 2Na(OH)(aq) + H2(g)
2K(s) + H2O(l) 2K(OH)(aq) + H2(g)
2Li(s) + 2H2O(l) 2Li(OH)(aq) + H2(g)
The pH paper showed a basic pH for the alkaline earth metals. This is because alkaline earth metal’s valence electrons only have one electron so the atom easily gives that electron away.
If cesium was added to water it would react the same as potassium; that as soon as it touched water it would ignite and explode, but the reaction may be stronger.
The reactivity of these metals increases as you go down the group. As the atom grows larger it becomes more reactive since the electrons are farther away from the nucleus.
Group IIA
Reactions in Water:
Pieces of solid magnesium and calcium were put in test tubes of water. Magnesium had no reaction with room temperature water or with boiling water. The calcium bubbled and formed gas and white precipitate. The pH balances were then tested.
Mg(s) + H2O(l) NR
Ca(s) + 2H2O(l) Ca(OH)2 + H2(g)
Reactions in Hydrochloric Acid:
Magnesium and calcium were placed in test tubes with hydrochloric acid. Both metals bubbled. The magnesium completely dissolved, while the calcium formed a white precipitant at the bottom of the test tube. The pH was tested.
Mg(s) + 2HCl(aq) MgCl2(aq) + H2(g)
Ca(s) + 2HCl(aq) CaCl2(s) + H2(g)
Reactions in heat/oxygen:
Two more pieces of the alkaline earth metals were subjected to heat and oxygen. Each piece of metal ignited and burned. The calcium took longer to ignite then the magnesium. The magnesium was then placed into water and the pH was then tested.
2Mg(s) + O2(g) 2MgO(s)
MgO(s) + H2O(l) Mg(OH)2(aq)
2Ca(s) + O2(g) 2CaO(s)
CaO(s) + H2O(l) Ca(OH)2(aq)
Calcium is more reactive than the magnesium, but they had similar reactions and pH.
They vary only slightly. Most of the reactions were the same but were slightly stronger with the calcium and the calcium oxide reacted stronger than the magnesium. The elements are more reactive as one descends the column.
The reactions of this group were different, but just as strong as those done with the IA group. They were less explosive, but had impressive reactions.
Group IIIA
Reactions in Water:
Boron and aluminum were placed into test tubes of water. The aluminum created effervescence while the boron had no reaction.
2Al(s) + 6H2O(l) 2Al(OH)3(aq) + 3 H2(g)
B(s) + H2O(l) NR
Reactions in Hydrochloric Acid:
The same was done only instead of water the elements were introduced to hydrochloric acid. The aluminum produced effervescence and the boron had no reaction.
2Al(s) + 6HCl(aq) 2AlCl3(aq) + 3H2(g)
Br(s) + HCl(aq) NR
Reactions in Sodium Hydroxide:
A piece of aluminum and of boron were placed into a test tube of sodium hydroxide. The aluminum created effervescence and the boron had no reaction.
2Al(s) + 2NaOH(aq) + 6H2O 2NaAl(OH)4 (aq) + 3H2(g)
Ba(s) + NaOH(aq) NR
Boron is not active compared to aluminum. Aluminum is beneath boron, which means it’s larger in size becoming more reactive.
The elements became less reactive in water the farther towards the right of the periodic table they are, and they become more acidic then basic.
Group IVA
Reaction in Water:
A piece of carbon, tin, and lead were placed in test tubes of distilled water. Five minutes were allowed for a reaction to occur, and none of them reacted in that time.
C(s) + H2O(l) NR
Sn(s) + H2O(l) → NR
Pb(s) + H2O(l) → NR
Reaction with Hydrochloric Acid:
Another piece of carbon, tin, and lead were placed in separate test tubes containing hydrochloric acid. Then the test tubes were placed in a hot water bath. Tin and lead slowly created effervescence, while carbon had no reaction
C(s) + HCl(aq) → CCl2(aq) + H2(g)
Sn(s) + HCl(aq) → SnCl2(aq) + H2(g)
Pb(s) + HCl(aq) → PbCl2(aq) + H2(g)
All three elements are non-reactive in water, but as they mix with acids they become reactive. Lead is the most reactive since it is the largest of these elements in this elemental group.
As the element closer to the right side of the table are less reactive since the valence shell progressively fills up, making it harder for other atoms to pull electrons from the valence shell.
Group VA
Reactions in oxygen/heat:
A small portion of phosphorus in a deflagrating spoon was ignited by a gas burner. The emitted smoke was then put in a flask that had distilled water at the bottom. The captured smoke was mixed with the water, then the pH tested.
P4(s) + O2(g) → P4O10(g)
P4O10(g) + 6H2O(l) → 4H3PO4(aq)
The pH paper resulted in being acidic. It reacted this way because phosphorus is three electrons away from having a full valance electron so it doesn’t react with water easily.
Reaction in Hydrochloric Acid and Water:
Pieces of bismuth were introduced into two test tubes; containing water and the other containing hydrochloric acid. After a few minutes no reaction occurred.
Bi(s) + H2O(l) → NR
Bi(s) + HCl(aq) → NR
Group VIA
Reaction in Oxygen/heat:
A small quantity of sulfur was introduced to burner by a deflagrating spoon. Once the sulfur was ignited the spoon was put into a flask containing a small amount of distilled water in the bottom. The smoke contained was then mixed with the water and the pH balance was tested.
S8(s) + O2(g) → 8SO2(g)
SO2(g) + H2O(l) → H2SO4(aq)
S8(s) + O2(g) → SO3(aq)
SO3 + H2O(l) → H2SO3(aq)
The pH paper resulted in being acidic. As with phosphorus, sulfur is getting closer to having a full valance shell becoming less reactive and more acidic.
Group VIIA
Reactions in Chlorine Water:
Chlorine water was added to a test tube containing potassium bromide and another test tube containing potassium iodide. After observing the color changes, hexane was added, to test to see if an actual chemical reaction occurred. In the potassium bromide: a yellow color was the starting color and ended with a pale yellow color. Potassium iodide however underwent a reaction, starting with the color brown and changing to the color purple.
KBr(aq) + Cl2(aq) → 2KCl(aq) + Br2(aq)
2KI(aq) + Cl2(aq) → 2KCl(aq) + I2(aq)
The hexane changed color because it was indicating as to whether a chemical reaction occurred or not. When potassium iodide is mixed with chlorine water a chemical reaction will occur, but not when potassium bromide is mixed with chlorine water.
The same experiment was completed only using bromine water that was added to a test tube containing potassium iodide and potassium chloride. The potassium iodide started out as a brown color and ended with a purple color. The potassium chloride however started out yellow and ended in a yellow color, but still underwent a chemical reaction.
KI(aq) + Br2(aq) → KBr(aq) + I2(aq)
KCl(aq) + Br2(aq) → KBr(aq) + Cl2(aq)
The hexane changed color again, because of the result in a chemical reaction occurring.
Based on this experiment it can be concluded that iodine is more reactive than bromine which is more reactive than chlorine. In the experiments iodine separated it-self from the potassium, meaning that it would rather be by itself, showing that it is more stable than chlorine and bromine.
Discussion
Going down the periodic table the elements are more reactive. This is due to the amount the atoms size is increase which causes the electrons be farther away from the nucleus making it easier for other atoms to pull the electrons away. The elements bigger but less reactive on the right side of the table than the left side. The atoms grow in size since the proton numbers are increase, but the valence electrons are becoming fuller, making it harder for other atoms to pull the electrons away.
As size increases the ionization energy increases, which makes an element less reactive. This is due to the fact that since the valence sub-shell is getting fuller, there are more electrons to pull from the atom.
References
1. General Chemistry Experiments: A Manual for Chemistry 204, 205, and 206, Department of Chemistry, Southern Oregon University: Ashland, OR, 2009
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